Composite materials and components are used in ever-increasing amounts in a wide variety of applications. For example, commercial aircraft are incorporating increasing amounts of composite materials into primary structure and secondary structure due to the favorable mechanical properties of composite materials. Such favorable mechanical properties may allow for a reduction in weight and an increase in payload capacity and fuel efficiency of an aircraft. In addition, the use of composite materials may extend the service life of the aircraft.
Laminated composite components may be joined together using several techniques. For example, composite components may be joined using mechanical fasteners which may require drilling fastener holes in the components using specialized drill bits. Following the drilling of the fasteners holes, disassembly of the composite components may be required to allow for de-burring and/or inspection of each fastener hole, followed by re-assembly of the composite components. Mechanical fasteners may be installed in the fastener holes and the fasteners may be tightened to a predetermined torque value. As may be appreciated, the use of mechanical fasteners for joining composite components may require multiple steps resulting in a time-consuming and labor-intensive process.
Composite components may also be joined together without mechanical fasteners by bonding the components together using an adhesive. The adhesive may be applied between the mating surfaces of the composite components to form a bond joint. The bond joint has a bondline thickness which ideally is relatively thin to minimize stress concentrations along the edges of the bond joint and to improve the shear strength and tensile strength of the bond joint. Occasionally, the mating surfaces of one or both of the composite components may have mismatched contours resulting in gaps in the bond joint.
Prior art methods of filling gaps between the mating surfaces of the composite components may include applying extra adhesive material between the mating surfaces and allowing the adhesive to flow into the gaps during the joining process. However, the extra adhesive material may increase the bondline thickness which may undesirably affect the strength properties of the bond joint. In another approach for filling gaps, specialized tooling may be developed for applying high compressive forces on the bond joint to push out the gaps between the mating surfaces. However, specialized tooling may increase overall manufacturing costs. In addition, the high compressive forces applied by specialized tooling may induce undesirable stresses in the composite components.
As can be seen, there exists a need in the art for a system and method for joining composite components which accommodates variations in the contours of the mating surfaces of the composite components while minimizing the bondline thickness.